From 865025d199ca9430851e512e99780c065dee635e Mon Sep 17 00:00:00 2001
From: Ivan Topolnjak <ivantopo@gmail.com>
Date: Mon, 21 Aug 2017 11:32:06 +0200
Subject: optimistic tick alignment for metrics ticker

---
 .../src/main/scala/kamon/ReporterRegistry.scala    | 26 +++++++++++++++++-----
 1 file changed, 21 insertions(+), 5 deletions(-)

(limited to 'kamon-core/src/main/scala')

diff --git a/kamon-core/src/main/scala/kamon/ReporterRegistry.scala b/kamon-core/src/main/scala/kamon/ReporterRegistry.scala
index ff135f60..eedec830 100644
--- a/kamon-core/src/main/scala/kamon/ReporterRegistry.scala
+++ b/kamon-core/src/main/scala/kamon/ReporterRegistry.scala
@@ -20,11 +20,10 @@ import java.util.concurrent.atomic.{AtomicLong, AtomicReference}
 import java.util.concurrent._
 
 import com.typesafe.config.Config
-import kamon.ReporterRegistry.SpanSink
 import kamon.metric._
 import kamon.trace.Span
 import kamon.trace.Span.FinishedSpan
-import kamon.util.{CallingThreadExecutionContext, DynamicAccess, Registration}
+import kamon.util.{DynamicAccess, Registration}
 import org.slf4j.LoggerFactory
 
 import scala.concurrent.{ExecutionContext, ExecutionContextExecutorService, Future}
@@ -32,6 +31,7 @@ import scala.util.Try
 import scala.util.control.NonFatal
 import scala.collection.JavaConverters._
 import scala.collection.concurrent.TrieMap
+import scala.concurrent.duration._
 
 sealed trait Reporter {
   def start(): Unit
@@ -59,6 +59,7 @@ trait ReporterRegistry {
 }
 
 object ReporterRegistry {
+
   private[kamon] trait SpanSink {
     def reportSpan(finishedSpan: FinishedSpan): Unit
   }
@@ -200,8 +201,22 @@ object ReporterRegistry {
         currentMetricTicker.cancel(false)
 
       metricReporterTickerSchedule.set {
+        val initialDelay =
+          if(registryConfiguration.optimisticMetricTickAlignment) {
+            val minimumInitialDelay = 2.seconds.toMillis
+            val currentTimestamp = System.currentTimeMillis()
+            val roundCurrentTick = Math.floor(currentTimestamp.toDouble / tickIntervalMillis.toDouble).toLong
+            val roundCurrentTimestamp = roundCurrentTick * tickIntervalMillis
+
+            if(roundCurrentTimestamp - currentTimestamp >= minimumInitialDelay)
+              roundCurrentTimestamp - currentTimestamp
+            else
+              (roundCurrentTimestamp + tickIntervalMillis) - currentTimestamp
+
+          } else tickIntervalMillis
+
         registryExecutionContext.scheduleAtFixedRate(
-          new MetricReporterTicker(metrics, metricReporters), tickIntervalMillis, tickIntervalMillis, TimeUnit.MILLISECONDS
+          new MetricReporterTicker(metrics, metricReporters), initialDelay, tickIntervalMillis, TimeUnit.MILLISECONDS
         )
       }
     }
@@ -310,13 +325,14 @@ object ReporterRegistry {
     private def readRegistryConfiguration(config: Config): Configuration =
       Configuration(
         metricTickInterval = config.getDuration("kamon.metric.tick-interval"),
+        optimisticMetricTickAlignment = config.getBoolean("kamon.metric.optimistic-tick-alignment"),
         traceTickInterval = config.getDuration("kamon.trace.tick-interval"),
         traceReporterQueueSize = config.getInt("kamon.trace.reporter-queue-size"),
         configuredReporters = config.getStringList("kamon.reporters").asScala
       )
 
-    private case class Configuration(metricTickInterval: Duration, traceTickInterval: Duration,
-      traceReporterQueueSize: Int, configuredReporters: Seq[String])
+    private case class Configuration(metricTickInterval: Duration, optimisticMetricTickAlignment: Boolean,
+      traceTickInterval: Duration, traceReporterQueueSize: Int, configuredReporters: Seq[String])
   }
 }
 
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